From patchwork Mon Jul 19 14:52:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 481295 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F1E3C07E95 for ; Mon, 19 Jul 2021 15:13:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2305561248 for ; Mon, 19 Jul 2021 15:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244961AbhGSOcU (ORCPT ); Mon, 19 Jul 2021 10:32:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:46606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244976AbhGSOas (ORCPT ); Mon, 19 Jul 2021 10:30:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4C74E6113A; Mon, 19 Jul 2021 15:11:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626707487; bh=6IIqv45VZhMDWIeJ4VV/kuRvyK4QUeRR9GmrKQlpsBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Aue9L1NYh/8JSsgrSZ4UCS/ciVPNw0Km04zuu5Nq2lsllNEW5kL1CnWKMCy/cfz3b wONK/Ne4vkwePVkApOj4/W6+N8Q1Id9M1uARZcZoZ1d0HUfLPeQueiPhRTq9tmirTS 3KdqqietWMnJamxA9i3Mj2ImHVIqxQB0jAoB+atw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sherry Sun , Sasha Levin Subject: [PATCH 4.9 185/245] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Mon, 19 Jul 2021 16:52:07 +0200 Message-Id: <20210719144946.382645003@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144940.288257948@linuxfoundation.org> References: <20210719144940.288257948@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sherry Sun [ Upstream commit fcb10ee27fb91b25b68d7745db9817ecea9f1038 ] We should be very careful about the register values that will be used for division or modulo operations, althrough the possibility that the UARTBAUD register value is zero is very low, but we had better to deal with the "bad data" of hardware in advance to avoid division or modulo by zero leading to undefined kernel behavior. Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20210427021226.27468-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/fsl_lpuart.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 5b6093dc3ff2..a4c1797e30d7 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1766,6 +1766,9 @@ lpuart32_console_get_options(struct lpuart_port *sport, int *baud, bd = lpuart32_read(sport->port.membase + UARTBAUD); bd &= UARTBAUD_SBR_MASK; + if (!bd) + return; + sbr = bd; uartclk = clk_get_rate(sport->clk); /*